The goal of this study is to show that it is possible to obtain Raman spectra of exogenous substances in skin in vivo and study their biochemical changes. Then the changes in the Raman spectra will be used to follow drug treatment and correlate with measurements of fluorescence and diffused reflectance. The initial experiment involves determining the quality and reproducibility of the Raman spectra obtained with the MIT instrument and comparison of the spectra with preliminary measurements taken with a FT-Raman (Bruker Instruments at Wellman Laboratory). Early steps include taking Raman spectra and difference Raman spectra in vivo and comparing with Raman spectra of the exogenous substances, cadevar skin as well as fluorescence spectra of the same samples.